Various designs for Venetian blinds within multi-pane windows have been developed. Such blinds may include a mechanism for raising and lowering the slats of the blind, which is typically provided along a side edge of the window, and a separate mechanism for tilting the slats, which is typically provided along a top edge of the window.
Some conventional designs include external magnets that are magnetically coupled to internal lift and tilt carriages. The external magnets run along the exterior surface of the glass panes and move the inner tilt and/or lift carriages as a result of the magnetic coupling therebetween. Movement of the tilt carriage moves tilt lines or a tilt ladder causing the slats of the blind to tilt and thereby open or close. Movement of the lift carriage moves the raise/lower lines of the blind causing the blind to raise or lower.
U.S. Pat. No. 5,826,638 to Jelic discloses a tilt mechanism for a venetian blind disposed between the glass panes of a double-glazed window. The tilting mechanism comprises an internal magnet located between the glass panes and an external magnet for moving the internal magnet. The internal magnet is coupled to a tilt assembly. The tilt assembly includes a shaft that extends across the width of the venetian blind. The shaft is coupled to a tilt ladder, which supports the slats of the venetian blind. The internal magnet is coupled to a nut that is mounted on a threaded rod. Linear movement of the nut in response to movement of the internal magnet causes the threaded rod to rotate, which in turn imparts rotation of the shaft thereby to open or close the venetian blind.
Various problems exist with such conventional designs. The external magnets of many such designs are abrasive against the glass pane. As such, movement of the external magnets over the glass panes often results in scratching and marking of the glass panes after extended use, rendering the window aesthetically unappealing. In addition, a significant amount of force is required to overcome the coefficient of static friction between the external magnets and the glass panes when the internal mechanisms are actuated. This may result in an operator applying excessive forces to the external magnets, which may break the magnetic union between the external magnets and the internal tilt and/or lift mechanisms.
In addition, conventional designs provide for two separate sliding knobs or control elements. It would be desirable to provide a single, external control element to accomplish the dual functions of (a) raising and lowering the slats and (b) adjusting the tilt of the slats.